2019 Porsche 911 vs. 2019 Mercedes SL

Detailed Review, Specifications & Comparison

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The 911 has a standard automatic post-collision braking system, which automatically applies the brakes in the event of a crash to help prevent secondary collisions and prevent further injuries. The SL doesn’t offer a post collision braking system: in the event of a collision that triggers the airbags, more collisions are possible without the protection of airbags that may have already deployed.

The 911 offers all-wheel drive to maximize traction under poor conditions, especially in ice and snow. The SL doesn’t offer all-wheel drive.

Both the 911 and the SL have standard driver and passenger frontal airbags, front side-impact airbags, driver and front passenger knee airbags, side-impact head airbags, front seatbelt pretensioners, four-wheel antilock brakes, traction control, electronic stability systems to prevent skidding, daytime running lights, rearview cameras, available crash mitigating brakes and blind spot warning systems.


The 911’s corrosion warranty is 7 years longer than the SL’s (12 vs. 5 years).


J.D. Power and Associates’ 2018 Initial Quality Study of new car owners surveyed provide the statistics that show that Porsche vehicles are better in initial quality than Mercedes vehicles. J.D. Power ranks Porsche fourth in initial quality, above the industry average. With 13 more problems per 100 vehicles, Mercedes is ranked 14th.

J.D. Power and Associates’ 2018 survey of the owners of three-year-old vehicles provides the long-term dependability statistics that show that Porsche vehicles are more reliable than Mercedes vehicles. J.D. Power ranks Porsche second in reliability, above the industry average. With 47 more problems per 100 vehicles, Mercedes is ranked 15th.

From surveys of all its subscribers, Consumer Reports’ December 2018 Auto Issue reports that Porsche vehicles are more reliable than Mercedes vehicles. Consumer Reports ranks Porsche 6 places higher in reliability than Mercedes.


The 911 has more powerful engines than the SL:



911 3.0 turbo 6 cyl.

370 HP

911 S 3.0 turbo 6 cyl.

420 HP

911 GTS 3.0 turbo 6 cyl.

450 HP

911 GT3 4.0 DOHC 6 cyl.

500 HP

911 GT3 RS 4.0 DOHC 6 cyl.

520 HP

SL 450 3.0 turbo V6

362 HP

SL 550 4.7 turbo V8

449 HP

AMG SL 63 5.5 turbo V8

577 HP

As tested in Motor Trend the 911 S 3.0 turbo 6 cyl. is faster than the Mercedes SL (automatics tested):



SL 550


Zero to 60 MPH

3.1 sec

4.1 sec

3.5 sec

Quarter Mile

11.5 sec

12.5 sec

11.8 sec

Speed in 1/4 Mile

120.5 MPH

115.2 MPH

123 MPH

The flat cylinder configuration of the boxer engine in the 911 lowers its center of gravity, enhancing handling stability. The SL doesn’t offer a boxer engine configuration.

Fuel Economy and Range

On the EPA test cycle the 911 S RWD Auto 3.0 twin turbo 6 cyl. (420 HP) gets better city fuel mileage than the SL 450 (22 city/28 hwy vs. 20 city/28 hwy).

Regenerative brakes improve the 911’s fuel efficiency by converting inertia back into energy instead of wasting it. The SL doesn’t offer a regenerative braking system.

The 911 GT2 RS’ optional fuel tank has 3.9 gallons more fuel capacity than the SL (23.7 vs. 19.8 gallons).


All-wheel drive, available in the 911, provides the best traction for acceleration in wet, dry, and icy conditions. In corners, all-wheel drive allows both outside wheels to provide power, balancing the car. This allows for better handling. The Mercedes SL is not available with all-wheel drive.

Brakes and Stopping

For better stopping power the 911’s brake rotors are larger than those on the SL:



SL 450/550


Front Rotors

16.1 inches

13.5 inches

15.8 inches

Rear Rotors

15.4 inches

12.6 inches

14.2 inches

The 911 stops much shorter than the SL:





70 to 0 MPH

139 feet

154 feet

Car and Driver

60 to 0 MPH

87 feet

109 feet

Motor Trend

Tires and Wheels

For better traction, the 911 GT2 RS/GT3 RS’ tires are larger than the largest tires available on the SL (F:265/35R20 & R:325/30R21 vs. F:255/35R19 & R:285/30R19).

For better ride, handling and brake cooling the 911 GT2 RS/GT3 RS has standard 20-inch front and 21-inch rear wheels. The SL’s largest wheels are only 19-inches.

Suspension and Handling

The 911 offers active sway bars, which help keep it flat and controlled during cornering, but disconnect at lower speeds to smooth the ride and offer greater off-road suspension articulation. This helps keep the tires glued to the road on-road and off. The SL doesn’t offer an active sway bar system.

For better maneuverability, the 911 GT2 RS’ turning circle is 2.6 feet tighter than the SL’s (33.6 feet vs. 36.2 feet).


The Porsche 911 may be more efficient, handle and accelerate better because it weighs about 450 to 700 pounds less than the Mercedes SL.

The 911 is 5.1 inches shorter than the SL, making the 911 easier to handle, maneuver and park in tight spaces.

The front grille of the 911 uses electronically controlled shutters to close off airflow and reduce drag when less engine cooling is needed. This helps improve highway fuel economy. The SL doesn’t offer active grille shutters.

Passenger Space

The 911 has standard seating for 4 passengers; the SL can only carry 2.

The 911 Cabriolet has 17.5 cubic feet more passenger volume than the SL (68 vs. 50.5).

Servicing Ease

J.D. Power and Associates surveys of service recipients show that Porsche service is better than Mercedes. J.D. Power ranks Porsche second in service department satisfaction. With a 6% lower rating, Mercedes is ranked 6th.


The 911’s instruments include an oil pressure gauge and a temperature gauge – which could save your engine! Often ‘idiot lights’ don’t warn you until damage has been done. The SL does not have an oil pressure gauge.

On extremely cold winter days, the 911’s optional heated steering wheel provides comfort, allowing the driver to steer safely and comfortably before the car heater warms up. The SL doesn’t offer a heated steering wheel.

Model Availability

The Porsche 911 comes in coupe and convertible bodystyles; the Mercedes SL isn’t available as a coupe.


Consumer Reports® recommends the Porsche 911, based on reliability, safety and performance.

J.D. Power and Associates rated the 911 first among midsize premium sporty cars in owner reported satisfaction. This includes how well the vehicle performs and satisfies its owner’s expectations. The SL isn’t in the top three.

The 911 Carrera GTS was chosen as one of Automobile Magazine’s “All Stars” in 2018. The SL has never been an “All Star.”

The Porsche 911 outsold the Mercedes SL by over four to one during 2018.

© 1991-2018 Advanta-STAR Automotive Research. All rights reserved.

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